Method for planarizing semiconductor substrates
First Claim
1. A method for planarizing an insulating layer and exposing underlying topographic features, said method comprising:
- applying a planarization layer over the insulating layer to thickness sufficient to form a substantially level surface;
uniformly etching the planarization layer with a first plasma down to about the interface between the planarization layer and the insulating layer; and
uniformly etching the remaining planarization layer and insulating layer with a second plasma selected to preferentially etch the insulating layer.
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Abstract
A method for planarizing an insulating layer overlying an irregular topographic substrate, e.g., a conductive layer, is planarized by use of a sacrificial planarization layer. The planarization layer is removed using an oxygen-containing plasma generated in a parallel electrode reactor operating at a low excitation frequency and high pressure. Once the interface between the planarization layer and the conductive layer is reached, a second plasma with a reduced oxygen content is employed to avoid overetching the planarization layer. It has been observed that oxidizing species liberated during the etching of the insulating layer, typically silicon dioxide, contribute to the oxidation and hence removal of the planarization layer. The process may be monitored by observing the spectral emissions from species generated or consumed during planarization or by changes in the optical interference pattern, allowing termination of the etch at the proper time to avoid over-etching and under-etching of the insulating layer.
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Citations
26 Claims
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1. A method for planarizing an insulating layer and exposing underlying topographic features, said method comprising:
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applying a planarization layer over the insulating layer to thickness sufficient to form a substantially level surface; uniformly etching the planarization layer with a first plasma down to about the interface between the planarization layer and the insulating layer; and uniformly etching the remaining planarization layer and insulating layer with a second plasma selected to preferentially etch the insulating layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for planarizing a silicon dioxide insulating layer and exposing underlying topographic features, said method comprising:
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applying an organic planarization layer over the insulating layer to a thickness sufficient to form a substantially level surface; etching the planarization layer with an oxygen plasma down to about the interface between the planarization layer and the insulating layer; and etching the combined planarization layer and insulating layer with a reduced oxygen plasma generated in a low frequency, high pressure parallel electrode reactor, whereby the insulating layer is preferentially etched relative to the planarizing layer. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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- 20. An improved method for planarizing an insulating layer on a semiconductor substrate, said method being of the type wherein an organic polymeric planarization layer is applied over the insulating layer and thereafter both the planarizing layer and the insulating layer are etched to leave a substantially planar surface, said improvement comprising etching the planarization and insulating layers with a low frequency, high pressure plasma in a parallel electrode reactor, wherein the frequency is below about 1 MHz and the pressure is above about 1 Torr.
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